Jean-Paul, Thanks for the information on Slate Dials. This is a different perspective and certainly is encouraging to dialist. Slate is readily available in San Diego CA at a tile and glass outlet. I may look into this some more. Tad Dunne replied about using glass as a substrate and I believe that the NASS published an article using glass. It is certainly easy to "frost" using the grit blasting technique. There is a quite a bit of info on the web concerning "sand Carving". http://www.rayzist.com is the web site of a company local to my area which provides materials and services to provide photopolymer blast masks for this industry. I have talked to their personel and they informed me that they have generated masks and blasting for I believe a large granite mural in a Chicago Post Office. This methode is rather "brute force" but the results are predictable in the hands of an experienced operator. I also believe that these techniques are also used in the manufacture of burial monuments.
Bob Jean-Paul Cornec wrote: > > About a comparison between different sorts of > stones for sundial carving, sundials of Brittany > in the west part of France are pretty > instructive. The region is rich with granite and > slate, and hundreds of dials are currently known. > The oldest sundials, dating back to the middle of > 16th century, are mostly carved on granite and > very few on slate. But from the very end of 16th > century on, carvers and dialists have totally > given up granite for slate. First because of the > bad resistance of granite to weathering. The few > remaining granite sundials look "erased" and > almost illegible, and they are vertical dials not > horizontal. And next because of the possibility > of easily cutting plates with any desired shape, > and of easy and very fine and beautiful carving > : some slate dials are really masterpieces. You > don't need special or heavy tools to carve slate > (or at least most of the varieties). Slate > resists much better to weathering, because, I > think, of its layer structure; for instance > don't forget that frost has no effect on slate > (in french it is said to be "ingélif" but I don't > know the english word for it). Existing dials, > even from 16th century, can be read as if they > have been carved last year. It is always amazing > to discover on a 1580 slate dial the slight lines > (less than 1 mm deep !) the dialist had drawn on > the plate to fix the place of the hours line, > digits or decoration before beginning to carve. > Granit lasts long but slate lasts even longer. > Another point. It is a spread , but quite false, > opinion that contrast of shadow on a slate plate > is low. It is quite the opposite : the shadow of > a style is very well visible, it is always darker > than slate surface that is never very dark but > more or less gray. The 500 or so slate dials > still remaining in Brittany (and in north-east of > France also) are living instances of this easy > reading. > > Regards > > Jean-Paul Cornec > 22300 LANNION > FRANCE > 48°44'24" N - 3°27'26"W
